# Arithmetic function

The Arithmetic function performs an arithmetic operation between two rasters or a raster and a scalar and vice versa.

The inputs for this function are the following:

• Input Raster 1
• Input Raster 2
• Operation

If you want to use a constant value for every pixel value in a raster, click the Raster drop-down arrow within the Generate raster from constant section of the dialog box and choose either Raster 1 or Raster 2. Then specify a value in the Constant text box.

The Operation options are

• Plus—Outputs the sum of all the corresponding pixel values for each raster.
`output = Raster1 + Raster2`
• Minus—Outputs the difference between the corresponding pixel values for each raster. This can be used to calculate change detection.
`output = Raster1 - Raster2`
• Multiply—Outputs the product of the corresponding pixel values for each raster. This can be used to perform some cost functions.
`output = Raster1 × Raster2`
• Divide—Outputs the divisible result between the corresponding pixel values for each raster.
`output = Raster1 ÷ Raster2`
• Power—Outputs the product of the corresponding pixel values raised to the power of the input raster or scalar.
`output = Raster1Raster2`
• Mode—Outputs the pixel value of all overlapping pixels that occurs the most. For example, if there are six bands in a raster, there will be six overlapping pixels. For the values 4, 5, 6, 4, 7, 9, the mode value is 4.

8/21/2013